by Ron Magid
Photos courtesy of Command Post Toybox and Miramax Films.

When Miramax opted to shoot Chicago in Toronto, artists at Toronto visual-effects facility Command Post Toybox were charged with transforming the modern Canadian city into the fabled metropolis of Al Capone circa 1929. "We got involved at the beginning, when they were storyboarding the visual effects, so we could offer a lot of creative advice," says visual-effects supervisor Raymond Gieringer (Panic Room, The Cell). "Chicago was filmed from December 2001 to March 2002, and we then spent six months working on 45 effects shots."

Some of the artists’ work involved straightforward rig removals, but the film also called for some big exterior shots of period Chicago streets that required a combination of 3-D animation, matte painting and compositing. Half of Command Post Toybox’s schedule was devoted to putting together two elaborate night shots depicting the neighborhood of Roxie Hart (Renée Zellweger).

The first opens on a tight shot of the actress in the window of a paddy wagon. As the vehicle pulls away, the camera moves back and the lens zooms out from Zellweger’s face to reveal a panoramic view of the street and then Chicago itself. "The plate was shot in Toronto," Gieringer says. "It was a real challenge because the lens starts off at a 50mm and eventually zooms out to an 18mm, which gives you a big vista. You can see for miles from Roxie’s rundown neighborhood all the way to downtown and the Wrigley building, and the shot is about 70 percent CG. We kept the vehicle, the street and a few extras, but we created everything else; that meant we had to track all the 3-D buildings in, figure out the lens distortion and texture everything to get the feeling right. We worked on that shot intermittently over the course of three months."

Understandably so, for it was no mere matte painting: the shot required more than 100 layers, which filled one of the facility’s Infernos. "That shot was also tough from a data-management perspective," Gieringer acknowledges. "Starting at the far back, we had several matte paintings of the skyline, plus we added the Wrigley and Tribune buildings and a slow-moving sky, so that was another five layers. Then we’re looking down a road that goes off to the horizon, with scads of buildings to the left and right that were all built and textured in CG. Then there were El-train tracks and an animated train, complete with digital people in its windows. We also created lampposts and the glow from the lamps, steam, foreground buildings and snow. It was a crazy amount of material."

Fortunately, not all of it was digital. In addition to shooting rolling background plates with the production’s second unit, Gieringer supervised the still photography of key landmarks in Chicago. "I spent a day and a half running around town shooting 4-by-5s of period buildings and streets, and that material gave us a big database to draw on for reference," he explains. "For the scene ‘Chicago after midnight,’ we had to take the modern Chicago skyline and rebuild it to look like it did during the Depression. The still photographer and I shot skylines from rooftops in Chicago using a Linhof Technika camera loaded with Kodak E100S slide film. The 4-by-5s gave us great resolution to pull from, and we used quite a number of those images as texture maps to wrap around our digital buildings."

A sister shot of Roxie’s street from a similar angle at an earlier time of day benefitted from the effects artists’ ability to repurpose a number of elements. "We built a few more buildings because the camera wasn’t in exactly the same position," Gieringer notes. "We either used the same elements or retextured them for different angles."

Another major effects setpiece was the night exterior of the famed Chicago Theatre. "We shot the background plate of the theater in Chicago," Gieringer recalls. "Its marquee is still very colorful, and it looks a lot like it did 70 years ago, but of course, the city around it was too modern. We therefore shot several period cars and extras in period clothing against greenscreen in Toronto. We then created much of the adjacent landscape, removed the modern buildings and inserted the period buildings. It’s a pretty cool shot.

"The challenge of a film like Chicago is to literally make the visual effects invisible," he concludes. "When the viewers’ suspension of disbelief erodes, you’re dead in the water. That’s the challenge that inspires me to come to work every day."